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developerWorks: Improvements in Kernel Development from 2.4 to 2.6

"In the three years of active development leading up to the
recent release of the new 2.6 Linux kernel, some interesting
changes took place in the way the Linux kernel is developed and
tested. In many ways, the methods used to develop the Linux kernel
are much the same today as they were 3 years ago. However, several
key changes have improved overall stability as well as quality.

"Historically, there never was a formal source code management
or revision control system for the Linux kernel. It's true that
many developers did their own revision control, but there was no
official Linux CVS archive that Linus Torvalds checked code into
and others could pull from. This lack of revision control often
left gaping holes between releases, where nobody really knew which
changes were in, whether they were merged properly, or what new
things to expect in the upcoming release. Often, things were broken
in ways that could have been avoided had more developers been able
to see changes as they were made.

"The lack of formal revision control and source code management
led many to suggest the use of a product called BitKeeper.
BitKeeper is a source control management system that many kernel
developers had already been using successfully for their own kernel
development work. Shortly after the first 2.5 kernels were
released, Linus Torvalds began using BitKeeper on a trial basis to
see if it would fit his needs. Today, BitKeeper is used to manage
the Linux kernel source code for both the main 2.4 and 2.5 kernels.
To most users, who may have little or no concern for kernel
development, this may seem insignificant. However, there are
several ways that users can benefit from the changes that the use
of BitKeeper have brought about in the methods used to develop the
Linux kernel..."